In other jurisdictions, acting in concert is generally understood to mean the intentional cooperation between two or more parties to exercise control of a listed company. And persons deemed to be acting in concert will have their voting rights combined for the purpose of calculating whether or not a mandatory disclosure and/or tender offer is required. Vietnamese securities regulations do not clearly contemplate or nor regulate the concept of “acting in concert”. As such, it is quite common in Vietnam for technically-unrelated persons to coordinate their voting to control (or influence the control) of a public company without having to disclose the coordination or making a public tender offer. This practice could potentially cause damages to public investors who are not aware of the potential change of control of a public company.
The provision under Vietnamese law which is most relevant to the “acting in concert” concept is the definition of a related person under the Enterprise Law 2014. Under the Enterprise Law 2014, a group of persons agreeing to co-operate among themselves to takeover a share of capital contribution, a share or interest in the company or to control the issuance of decisions by the company will be considered as a related person of the company. However, the Enterprise Law 2014 only considers a group of concerting parties as a related person to the company that such parties are trying to control but not as related persons between themselves.
Update 30 April 2017 - Remove the sentence "In addition, it is not clear if the concept of “related persons” under the Enterprise Law 2014 would apply to a public listed company since the Securities Law 2006 has its own definition of related persons." since under Decree 71/2017, a related person includes both related persons under the Securities Law 2006 and Enterprise Law 2014.